Hyperplastic changes of the bronchial arteries may take the form of a racemose arteriovenous angioma or result from chronic bronchitis. Clinically, recurrent haemoptysis is a striking feature occurring in otherwise fit patients. The two forms can be distinguished by bronchial arteriography because of the difference in the appearance of the vessels. In the one condition there are circumscribed areas of arterial and venous, vascular abnormalities, in the other there is vascular hyperplasia, which is less clearly circumscribed. In both forms, broncho-pulmonary, i.e. arterio-venous anastomoses can be demonstrated; these may be considered as the cause of the haemoptyses.